While RSS.com does provide industry-leading analytics to podcasters, it is not currently possible to accurately determine how many subscribers a show has. This is because most podcast players, apps, and directories either do not track subscribers or they don't report those numbers.
However, you can estimate the number of subscribers for your show, and RSS.com provides a new first-of-it's-kind metric called Subscribers, which counts the number of individual listener devices that download or stream your show. Subscribers number is the average of the first 24 hours unique downloads for your last 3 episodes.
To get a rough estimate of your show's subscriber numbers, keep an eye on the number of downloads your show receives in the first 24 hours after you publish a new episode.
If your show is released every Friday at 6:00 am and you get around 100 downloads every Friday morning week after week, then it's safe to assume that you have roughly 100 subscribers (keep in mind that promoting the episode on social media and through other channels can lead to new listeners who may not subscribe to the show).